1. Field of the Invention
The invention relates to a gearshift unit for a transmission of a motor vehicle including a shift lever for shifting the gears of the transmission, a gear shift assist unit for assisting the shift movement of the shift lever and a control device for controlling the operation of the gear shift assist unit.
2. Description of the Prior Art
DE 198 39 854 A1 discloses a gearshift unit for a transmission of a motor vehicle. Transmissions can be shifted by a driver of a motor vehicle by means of a gearshift lever. In order to reduce the shift force that has to be exerted by the driver of the vehicle, the gearshift unit has a pneumatic gearshift servo-assist unit, which is fed by a compressed air system of the motor vehicle. The gearshift servo-assist unit is capable of exerting an additional shift force, which supplements the shift force which the driver exerts via the gearshift lever. The gearshift unit is designed so that the additional shift force is exerted only when a drive connection between a power unit and the transmission is interrupted by means of a clutch. In addition a control device of the gearshift unit actuates an electro-magnetic valve of the gearshift servo-assist unit so that the additional shift force only acts when, in the desired gear, the engine speed does not exceed an engine speed limit.
It is the object of the present invention is to provide a power gearshift unit which safely prevents damage to the transmission by undesirable shifting actions.